Knuckle pushups aren't that different from regular ones, but the change in the hand position works the muscles differently and increases the difficulty of the exercise. Mixed martial artists often perform knuckle pushups as they more closely match the punching movement, but adding variety to your pushup routine can keep you interested in your workout and help you tone your arms, chest and back.
Knuckle pushups follow the same basic form as regular pushups. With regular pushups, you rest on your hands and the balls of your feet, with your body making a straight line between your neck and your ankles. Your hands are slightly wider than your shoulders, and sit at shoulder level. Knuckle pushups have your hands in a narrower stance, directly under your shoulders. Make a fist with each hand and rest them on the ground with your palms facing inward. Your arms are straight through the wrist, unlike regular pushups, where your wrists sit at a 90-degree angle.
Each style of pushup includes basic variations. Instead of doing a plain regular pushup, lift your hands and clap at the top before returning to the regular stance. You can also do 100 pushups or single-leg pushups. Knuckle pushups raise your body slightly higher off the floor than regular pushups, which makes it easier to bring a knee forward as you lower. You can also turn your hands so the palms face backward or alternate sides as you lower your body -- move your chest toward your left fist, lift, then down to the right fist. To build a more powerful punch, lower your body only slightly in the knuckle pushup position and hop up at the top of the move so both fists leave the floor by at least 1 inch.
Regular pushups focus the motion on the shoulders and triceps, with some back and chest muscle work as well. Changing the hand position to your knuckles brings your arms in slightly, bringing more of the workout to your chest and less to your back. The act of holding your wrist straight helps build your forearms, and the triceps work a bit harder by helping your balance on a smaller surface: your closed fist instead of your open hand.
Mixed martial artists use knuckle pushups to help build tougher skin across their knuckles to reduce the chance of injury during a fight. However, performing knuckle pushups on a mat or soft surface is ideal for non-fighters. Both pushups build muscle and raise your heart rate for a cardiovascular workout, and they both require no special equipment. If you suffer from wrist pain, knuckle pushups might be a better option for you. The bent position of the wrist in regular pushups can cause or increase wrist pain, but the straight position in knuckle pushups helps build the muscles in the wrist and forearm to help prevent sprains and injuries.